1. Field of the Invention
The present invention relates to a splitter switch for humbucking musical instrument pick-ups and, more particularly, to a splitter switch arrangement for a pick-up, used in conjunction with a capacitor, whereby switching from a humbucking arrangement to a single coil arrangement can be effected without decreasing the overall signal level of the pick-ups.
2. Description of the Prior Art
The present invention relates broadly to electrical musical instruments of the stringed type. It is particularly applicable to an electric guitar or a similar musical instrument having a plurality of stretched strings extending across a body and a neck, between the head of the instrument and a bridge assembly connected to the body, in which the strings are caused to vibrate by plucking or picking same.
In order to derive an output from such an electrical guitar or other similar electrical musical instrument, the instrument is conventionally provided with an electromagnetic pick-up comprising a number of magnetic elements (pole pieces) having wound therearound a conductive coil. Typically, one such magnetic element is disposed directly beneath each string of the instrument. The strings are constructed of a magnetizable substance, such as steel, and, therefore, become part of the conductive path for the magnetic lines of flux of the pole pieces. Accordingly, when any of the strings are caused to vibrate, this causes a disturbance in the magnetic field of the associated pole piece. This has the effect of generating a voltage in the conductive coil, which voltage may be suitably amplified and transmitted to a loudspeaker system.
With such an electromagnetic pick-up construction, a number of problems exist. Electric guitars and other similar electrical musical instruments are used in areas having strong magnetic fields from lighting fixtures, motors, transformers and the like, and these magnetic fields are sensed by the pickup as an extraneous noise source. In the United States, such source typically has a frequency of 60 Hz, the usual power line frequency. These magnetic fields induce voltages in the coil which also are amplified and transmitted to the loudspeaker system, manifesting themselves in an objectionable hum.
In order to overcome this problem, it is known to provide a pick-up for an electrical musical instrument including a pair of identical pick-up assemblies, each having a plurality of magnetic pole pieces and a coil, the pick-up assemblies being positionable in parallel, spaced, closely adjacent relationship. All of the pole pieces of one of the pick-up assemblies have their north poles adjacent to the strings and their south poles relatively remote from the strings, whereas all of the pole pieces of the other pick-up assembly have their south poles adjacent to the strings and their north poles relatively remote from the strings. The coils of the two pick-up assemblies are wound in opposite directions and the two coils are connected either in series or in parallel. Because the direction of current flow in each coil is governed by the magnetic polarity, the direction of current flow in one coil is opposite to that of the other coil for each string. However, since the directions of the windings of the two coils are opposite, the signal induced in each coil as a result of string vibrations is additive and the output signal is the sum of the signals induced in each coil. If the coils are connected in series, the output signal is the sum of the voltages induced across each coil. If the coils are connected in parallel, the output signal is the sum of the currents induced in each coil.
On the other hand, signals picked up by the coils from power line sources produce currents in the coils which are independent of the magnetic polarity and, accordingly, such power line sources produce voltages that are in phase. However, since the coils are wound in opposite directions, these in-phase signals cancel and the output signal is the difference between the power line signals induced in each coil. This means that any noise from power line sources which is otherwise manifested as an objectionable hum, is effectively reduced or cancelled. It is for this reason that such an arrangement is typically characterized as a humbucking arrangement.
While humbucking pick-ups have come into common use in electric guitars and other similar electrical musical instruments, there are problems associated therewith. For example, since the pick-ups have different positions along the length of the strings, they respond differently to the harmonics of the string vibrations. This fact, as well as others which result from the interaction between the coils, results in a pick-up in which the two coils together do not provide as clean and as sharp a response, especially at high frequencies, as is the case with a single coil.
Therefore, it has become common practice with some instrument makers to provide a switch, commonly referred to as a splitter switch, which allows the musician the option of short circuiting one coil of the humbucking pair. When this is done, the remaining active coil clearly has a cleaner and better response to high notes and this is much preferred by many musicians. On the other hand, when the splitter switch is closed to short circuit one of the coils, the output signal is effectively cut in half. That is, in a series connection, the voltage output is immediately cut in half, whereas with parallel coils, the current output is immediately cut in half. Since the overall signal level is cut in half, closing of the splitter switch immediately and significantly reduces the volume output of the loudspeaker system. Most musicians find this to be a considerable nuisance because movement of the splitter switch requires immediate readjustment of the volume level.